The laser shock peening (“LSP”) process, a substitute process for traditional shot peening, is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of materials by impacting the material with enough force to create plastic deformation. The residual stresses created by the LSP process increase a material's resistance to fatigue and stress, and the LSP process can be used to strengthen and harden materials. LSP uses high energy laser pulses to lase both transparent and opaque overlays on a surface of a workpiece to generate a plasma plume and cause a rapid rise of pressure on the surface of a workpiece. This pressure creates and sustains a shockwave, which propagates through a workpiece material. The shockwave generated by LSP induces cold work into the microstructure of the workpiece material and contributes to the increased performance of the workpiece material. As the shockwave travels into the workpiece, some of the energy of the wave is absorbed during the plastic deformation of the workpiece material. This is also known as cold working. The shockwave permanently stretches the internal structure of the workpiece material. This plastic deformation generates compressive residual stresses in the workpiece material, and increases the strength of the workpiece material. LSP uses a laser pulse width of about 5 nanoseconds (ns) to about 40 ns and a typical spot diameter for a laser beam in LSP is about 1.0 to about 6.0 mm. Fluence is the measure of energy delivered per unit area, and in LSP applications, fluence is typically over 100 J/cm2.
The present application appreciates that customizing a laser pulse for LSP applications may be a challenging endeavor.